Causes of Orange Peel

Understand and avoid this common spraying flaw.

by Bob Flexner
pages 62-63

Orange peel is the most universal defect in a sprayed finish. It is a bumpiness on the surface that resembles the skin of an orange – hence the name.

No matter what brand or quality of spray gun you’re using, or how well you clean and tune the gun, or what you’re spraying, you can still get orange peel. You want to avoid it if possible.

The problem is that there are so many causes (and thus so many solutions) that eliminating the problem can become very confusing.

Here’s one manufacturer’s list of causes:
■ Liquid material is too thick
■ Failure to deposit a wet coat
■ Spray gun is moving too rapidly
■ Insufficient air volume
■ Insufficient air pressure
■ Incorrect fluid nozzle
■ Incorrect air cap
■ Holding spray gun too far away
■ Holding spray gun too close
■ Thinner evaporates too fast
■ Too much draft
■ Temperature too high
■ Temperature too low
■ Humidity too low.

That’s a lot of causes. All can be correct, but there are so many that I’ll bet you stopped reading after the first two or three and skipped to this paragraph.

Blog: Read Bob Flexner’s blog.
In Our Store: “Flexner on Finishing” – 12 years of columns illustrated with beautiful full-color images and updated, and “Wood Finishing 101.”

From the February 2018 issue